Conventionally, there has been known a method of manufacturing a semiconductor device which includes a step where lattice defects are introduced into the inside of a semiconductor base substrate by irradiating an electron beam to the semiconductor base substrate (see patent literature 1, for example).
As shown in FIG. 17, the conventional method of manufacturing a semiconductor device includes: an MOS structure forming step; a surface metal layer forming step; a patterning step; an electron beam irradiating step; and an annealing step in this order. That is, the conventional method of manufacturing a semiconductor device includes: the MOS structure forming step (see FIG. 18A and FIG. 18B) where a gate electrode 924 is formed on a first main surface side of a semiconductor base substrate 910 with a gate insulation film 922 interposed therebetween and, thereafter, an interlayer insulation film 926 is formed so as to cover the gate electrode 924; the surface metal layer forming step (see FIG. 19A and FIG. 19B) where a surface metal layer 928′ is formed over the interlayer insulation film 926; the patterning step (see FIG. 20A and FIG. 20B) where the surface metal layer 928′ is patterned; the electron beam irradiating step (see FIG. 21A and FIG. 21B) where lattice defects are formed in the inside of the semiconductor base substrate 910 by irradiating an electron beam to the semiconductor base substrate 910; and the annealing step (not shown in the drawing) where the lattice defects in the semiconductor base substrate 910 are repaired by heating the semiconductor base substrate 910 in this order. In the electron beam irradiating step in the conventional method of manufacturing a semiconductor device, an electron beam is irradiated to the semiconductor base substrate 910 from a second main surface side of the semiconductor base substrate 910.
In this specification, “lattice defects are repaired” in the annealing step does not mean that the all lattice defects are repaired, but means that a predetermined number of lattice defects necessary for properly controlling a lifetime of a carrier at the time of turning off a parasitic built-in diode are made to remain and other lattice defects are repaired.
In the conventional method of manufacturing a semiconductor device, in the electron beam irradiating step, the lattice defects are formed in the inside of the semiconductor base substrate 910. Accordingly, a lifetime of a carrier at the time of turning off the parasitic built-in diode is properly controlled and hence, it is possible to manufacture a semiconductor device where a parasitic built-in diode recovery loss is small.